One big thing for me is that I trust the FreeBSD devs to not completely reinvent things unless they're sure it's an improvement.
I got sick of the churn in Linux, having to relearn things all the time and then find out when I'm done that it's not any better, just different.
Things I learned how to do in FreeBSD a decade ago still work. For example, to get a NIC configured I can either put one or two lines of text in rc.conf, (which I have pretty much memorized at this point), or stop and learn what RedHat thinks is the coolest way to do network config this year.
Watching iptables get replaced was a really depressing example of that, after the developers swore that "this time we got it right" when replacing ipchains......
In fairness IPTables has been around and considered stable for, what, more than a decade and a half now?
I'm sure there are great many things that I consider "right" now that will be wrong in 15 years time either due to changes in the environment in which they work or me otherwise learning new information or developing new techniques over time.
I haven't had reason to use nftables yet (beyond the default config in a distro), but if it's in any way closer to PF, then it's vastly superior to iptables in my eyes. I spent a while configuring OpenBSD firewall/VPN gateway boxes about a decade ago, and the all around superiority of PF was astounding.
I got sick of the churn in Linux, having to relearn things all the time and then find out when I'm done that it's not any better, just different.
Things I learned how to do in FreeBSD a decade ago still work. For example, to get a NIC configured I can either put one or two lines of text in rc.conf, (which I have pretty much memorized at this point), or stop and learn what RedHat thinks is the coolest way to do network config this year.